Trolls during the Middle Ages

Church painting of trolls from Voldby Church, DenmarkThere are many Scandinavian localities with the word 'troll' in them, incl. troll forests, troll hills, troll swamps, places often uninhabitable and connected with a local tale of trolls or giants. The photo below is from Troldeskoven (Troll Forest) in Northern Sealand, Denmark, a forest famous for its strange wind-bent trees. Just like the stories of giants to explain various topological characterics, these names should not be taken to serious, more as playful storytelling. There is no evidence that these names were ever taken serious.

The Christian church fought an impossible fight to eradicate the heathen underground creatures and it is said that until the end of the Middle Ages there were still traces of the old Norse religion in Scandinavia - the same religion that has been "revived" in Iceland recently. The Church had to build its churches on old sacred places and trolls were seen as manifestations of the Devil - but popular folklore with its more humanised trolls survived till the beginning of the industrial age.

As mentioned elsewhere, trolls could also help humans building their churches. Thus Lund Cathedral in Skåne, Sweden, is allegedly built by a giant or troll called Finn and in the crypt his work is commemorated with this stone figure holding one of the pillars:

In this illustration by Niels Skovgaard to a poem by the Danish poet Poul Martin Møller a poor saint who has a troll build a church for him, has to learn the troll's name to save both his own sight and the troll-built church from being destroyed by the troll again. Fortunately he overhears the troll mother saying her husband's name Find to their troll child. And thus the church is saved.